A horizontal vibration detector using a leaf spring pendulum and magnetic levitation of a permanent magnet

悬浮力相当于摆锤的重量。悬浮采用由N，S带材交替磁化的永磁体。该摆已制作完成，并通过实验进行了评价。实验结果如下。1.S摆的原型达到了11个以上的自然周期。2.用磁力弹簧改变了原型的自然周期。这一时期的数值与理论计算一致。3.样机具有反馈控制电路、反馈控制线圈和电容式位移传感器，可作为伺服式地震仪使用。4.利用磁悬浮地震仪进行了微震观测，验证了磁悬浮地震仪对微震的测量能力，并对控制电路的制作方法进行了改进，进一步降低了噪声。控制电路采用微波电路通常使用的带状线技术。带状线可以改善电路板上的器件之间的隔离。控制电路的直流10V电源结构也进行了改进，以获得长期电压稳定和低噪声。改装的这一特点是使用连接在直流调节器之间的电池。其中一个调节器是将交流100V转换为直流13V。经过这个电路，就有了电池。直流10V调整器连接到电池。该电源在1赫兹以上的噪声水平约为-140dBV，长期电压稳定度为10^&lt；-6&gt；。

levitation for a pendulum weight. The levitation employs permanent magnets magnetized by N, S strip, alternatively. This pendulum has been built and evaluated by experiments. The results of the experiments are as follows. 1. The prototype of the pendulum achieved a natural period more than 11 s. 2. The natural period of the prototype was changed with a magnetic spring. These values of the period were consistent with theoretical calculations. 3. The prototype with a feedback control circuit, a feedback control coil and a capacitance displacement sensor worked as a servo-type seismometer. 4. The observations using the magnetic levitation seismometer have been carried out and showed capacity to measure microseisms.In addition to the above mentioned results, fabrication method for the control circuit was improved to achieve further low noise. The control circuit employs Strip Line technology that a microwave circuit usually uses. The Strip Line can improve isolation between devices on the circuit board. The structure of a DC 10 V power supply for the control circuit was also modified for obtaining long term voltage stability and low noise. This feature of the modification is using a battery connected between DC regulators. One regulator of them is to convert from AC 100V to DC 13 V. After this circuit, there is the battery. The DC 10 V regulator is connected to the battery. This power supply showed the noise level above 1Hz is about -140 dBV and the long-term voltage stability is order of 10^<-6>.